Classic Time Division Multiplex (TDM)-based telephony switches allow service providers to provision tariff, or billing, information. These tariffs apply to any number of applications, such as local calls, long distance calls, operator-assisted calls, service calls, Integrated Services Digital Network (ISDN) calls, and other types of calls. Through a capability referred to as hardware metering, tariff information may be sent to a user's telephone or a device associated therewith, which processes the information to provide charge information to the user or help account for the call. For example, the information may be used to alert a pay phone that additional money is necessary to establish or continue the call. The tariff information is generally provided to the telephone or to an associated device as a series of pulses, which correspond to the tariff being incurred. The pulses are used to calculate the tariff and control how to process the call or control information provided to the user.
Generally, the call tariff models divide a call into a number of phases. Each phase represents a different tariff rate. The duration of a phase may be explicitly defined or may be infinite. An infinitely long phase duration means the tariff defined for the phase applies for the remainder of the call. The tariff itself is defined by a charge rate, expressed in an amount of currency per unit of time, for each phase and optionally a charge interval. The charge interval allows the provider to specify how frequently charges are assessed during the phase. Call tariff models may also include one-time charges, such as a call setup charge, or a mid-call add-on charge, which may be applied to charge for events, such as invocation of a supplementary feature during the call. In addition to the tariff rate information, the service provider must be able to specify the conversion rate for mapping currency charges-into pulse counts. The result of this conversion is referred to as a tariffed pulse rate (TPR).
Generally, the TPR is specified in units of pulses per second, and each phase has a specific TPR. In a traditional Public Switched Telephone Network (PSTN), these pulses are provided over a dedicated circuit-switched connection. As the PSTN is replaced by packet-based network architectures, this process of providing pulses in a metering process faces new challenges. Given the inherent nature of packet-based networks, errors in metering accuracy are exacerbated due to latency caused by routing equipment in the packet network, as well as the potentially greater distances over which metering information must be conveyed. Further, the potential for packet loss and the subsequent need for packet retransmission increases the likelihood of inaccuracy in the metering process.
Current metering processes in packet networks rely heavily on the use of different messages to handle different aspects of the call, such as the setup and add-on events, as well as each phase of the call. The messaging associated with the metering process impacts available bandwidth and processing resources. Further, the complexity of the metering process often requires an effective fractional pulse rate over a given phase. At this point, there is no effective mechanism for handling fractional pulse rates in a packet-based environment. Accordingly, there is a need for an efficient metering process in a packet environment that is capable of addressing one or more of the limitations set forth above.